Telegraph signaling system



Aug. 11, 1925.

J.- M. FELL ET AL TELEGRAPH SIGNALING SYSTEM ATTORNEY Patented Aug. 11, 1925.

UNITED STATES,

PATENT OFFICE.

JOHN M. FELL, OF HACKEN'SACK, NEW JERSEY, AND RALPH E. PIERCE, 0]? LARG MONT, NEW YORK, ASSIGNO'RS TO AMERICAN TELEPHONE AND TELEGRAPH COM- PANY, A CORPORATTONOF NEW YORK.

TELEGRAPH SIGNALING SYSTEM.

Application filed March 15, 1920. Serial No. 365,935.

To all whom it may concern:

Be it known that we, J OHN M. FELL and RALPH E. PIERCE, residing at Hackensack and Larchmont, in the counties of Bergen and Westchester and States of New Jersey and New York, respectively, have invented.

certain Improvements in Telegraph Signaling Systems, of which the following s a specification,

This invention relates to telegraph signaling systems and particularly to means for preventing the undesirable reaction between the polar relays of a duplex system when a receiving operator opens hls key 1n order to get control of the circuit.

One of the most common faults found in operating duplexsets on a half duplex basis is the mutual reaction between the transmitting and receiving relays of the duplex set. This reaction occurs when an operator who is receiving signals from another station at the other end of the circuit opens his key in 'order' to get control of the circuit. This reaction manifests itself in a chattering or buzzing of the relays arising from the vibration of the armatures of the relays be tween their respective marking and spacing contacts when the transmitting keys at opposite ends ofthe line are simultaneously in the open position. In the standard polar duplex set this fault is remedied by means of a back contact repeating sounder operated by a pole changer which closes the receiving circuit whenever the pole changer is open irrespective of whether or not the circuit is closed at the receiving relay. The set is thus locked against the said mutual re action. Our invention is particularly re lated to a circuit of the type disclosed in the copending application of J. M. Fell, Serial Number 365,911, filed March 15, 1920, which provides for the use of polar relays as transmitting pole changers. It is the object of our invention to provide a simple. and effective means to prevent the reaction between the relays shown in the Fell circuit, thereby improving the breaking operation so as to enable a receiving operator to get control of the circuit promptly, thus tion when read in connection with the attached drawing which shows one form of its embodiment.

In the drawing X and Y represent two repeater stations which are joined by the line circuit L At the stations X and Y are terminated the loop circuits L and L respectlvely, which serve to connect the telegraph substations A and B respectively with the said repeater stations. At substation A the equipment comprises a key K,, a relay R a sounder S and a source of direct cur-' rent, B,, the polarity of which is opposite to that of battery B associated with relay R,

at station X. At substation B the equip- The equipment at each repeater station.

embraces a group of two polar relays having polarized sounders connected in a leak circuit from the armatures to ground and having the usual artificial lines adapted to balance the circuits connected with the said polar relays. 7 Thus at station X, B and R represent two polar relays each having two windings connected differentially. The windings 1 and 2 of relay R are connected respectively with the loop circuit L and with the artificial line AL,. The midpoint, or apex of the said windings is connected with the armature of the polarized sounder S the windings of which are connected in a leak circuit from the armature of-relay R to ground. Windings 3 and 4 of relay R are connected respectively with the line circuit L and with the .a'rtificial line AL,. The apex of these windings is connected, with thearmature of relay R The armature of relay R is connected with the normal contact 9, of the sounder S and the B Associated with the relays R and R are the marking batteries B and B respectively and the spacing batteriesB and B, respectively. The equipment at the repeater station Y is similar, to that at station X, comprising the polarized relays It, and It, having windings 56 and 78 respectively.

.Also associated with these relays are the artificial lines AL and AL, and the sounders S and S, respectively. Marking batteries B and B and spacingbatteries B and B are associated with the contacts of the armatures of relays R and R respectively.

Having in mind the foregoing description of the parts of the apparatus comprising the circuit in which this invention is embodied, the invention will be clear from the following description of the mode of operation of this circuit.

Let it be assumed that station A is transmitting signals and that station B is receiving signals. That is to say, that key K is being closed and opened to transmit marking and spacing signals and that key K remains closed for the reception of the transmitted signals. Since batteries B and B are of opposite polarity, the closing of key K will cause current to flow over a circuit comprising battery 13,, relay R key K loop L winding 1 of relay R contact 9 of sounder S marking contact of relay R and battery B to ground. Current will also flow through winding 2 and artificial line ALL to ground. The difference in value and direction of the currents in windings l and 2 will be such as to hold the armature of relay R upon its marking contact. Since batteries B and B associated with relays R and R respectively are opposed to each other no current will flow through the line L or through windings 3 and 5 of relays R and R respectively. Current flowing in windings 4 and 6 of the said relays will maintain the respective armatures upon their marking contacts. Since batteries B and B are in conjunction, current will flow over the line L and produce a marking signal at the substation B. If a spacing signal is transmitted from station A to station B no current will flow through winding 1 of relay R and in consequence thereof the armature of this relay will be moved to its spacing-contact as the result of the current in the winding 2. This results in the connection of the battery B to the line L and since B and B are in conjunction current will flow through the line L and the windings connected thereto. Current will also flow in windings 4 and 6 of relays R and R respectively. The diiierence in valueand direction of the currents in windings 3 and 4 will hold the armature of relay R upon its marking contact. The difference in value and direction of the currents in windings 5 and 6 will move the armature of relay R to its spacing contact. This results in the connection of the battery B to the line L; and since B and B are opposed to each other no current will flow through the said line. In consequence thereof the spacing signal transmitted from substation A will be received at station B. It is desirable to point out that the sounders S and S respond to the transmission of signals from station A to station B. SoundersS and S respond to the transmission of signals from station B to station A. Thus when a marking signal is being sent from A to B the armature of S will remain on contact 9 and that of S on its marking contact. The transmission of a spacing signal from A to B moves the armature of S to contact 10 and that of S to its corresponding spacing contact. Sounders S and S operate in a similar manner when signals are transmitted from B to A.

Let it be assumed now. that when station A is transmitting a spacing signal the operator at station B opens his key K for the purpose of getting control of the circuit. By the opening of key K the armature of relay R will be moved to its spacing contact as a result of the flow of current from battery B Since key K is opened at the same lnstant the armature of relay R, will be moved to its spacing contact as the result of the flow of current from battery B Since now batteries B and B are opposed to each other no current will flow in the line L or windings 3 and 5 of relays R and R respectively, and the flow of current in windings 4 and 6 respectively will be in such direction as tov move the respective armatures to their spacing contacts. Considering repeater station X the flow of current from battery B through winding 2 would be in such direction as to tend to move the armature of relay R to its marking contact if contact 9 remained closed. However, when the armature of relay R is on its spacing contact, the polarized sounder S is operated and the apex of windings 1 and 2 of relay R is connected through the armature of sounder S and contact 10 to battery B The flow of current through the winding of relay R is then in such'direction as to hold its armature on its spacing contact. The operation of sounder S at station Y acts in a similar manner to prevent the movement of relay R By" means of this invention the buzzing or chattering of the polar relays resulting from the vibration of their armatures between their respective contacts when both keys are open is prevented by the interposition of the polarized sounder or equivalent switching means which reverses the polarity of the current flowing through the windings of one of the relays. Heretofore in duplex till circuits in which no s ial preventive. means were employed this buzzin would continue until the armatures ha swung sufiiciently out of. phase to rest simultaneously 'upon contacts of opposite polarity.

vent the interference by incoming signals with a spacing signal transmitted for the purpose of obtaining control of the circuit. For example, if station A is sending signals to station B and the key K at station B is opened to getcontrol of the circuit, the reception of the signal at repeater station Y, .correspondingto the closing of key K will cause relay R to connect battery B, through its armature and the armature of sounder S, to the apex of windings and 8 of relay R Since key K is opened in order to get control of the circuit, no current will flow in line L and the direction of current in winding 8 will be such as to operate relay R moving its armature .to its spacing contact. This serves to connect battery B to the armature of relay R and operates the sounder S which connects. battery B, to the apex of windings 7 and 8 of relay R over a circuit which avoids the contacts of relay R If a spacing signal is now received at repeater Y over line L the relay R will have a spacing battery connected to its armature, but

the connection between this armature and the apex of the windings 7 and 8 of relay R is broken at the contacts of the polarizedv sounder, and in consequence, thearmature of relay R remains on its spacing contact. If this connection had not been broken the spacing current from battery B would haye passed through winding 8of relay R in such direction as to move its armature to its marking contact, and a marking signal would have been sent from this relay instead of a spacing signal, corresponding to the open position of key K It will be seen, therefore, that by using a polarized switching device such as the sounder S,, the interference by incoming signals with the break operation is thereby avoided.

Although this invention has been disclosed in a particular form in which a polarized sounder, connected into a leak circuit from the armature of a polar relay, serves to prevent the interference heretofore described, it is to be understood that a relay may be substituted for the said sounder, or that the function of the sounders may be performed by relays connected in the loops L and L in series with said polar relays, or by other and different arrangements without departing from the spirit and scope of the appended claims.

What is claimed is:

1. In a telegraph si aling system, the combination with two ine circuits of two polar relays, each individual to a line circuit and each having an artificial line designed to balance its respective line circuit, sources of potential of opposite polarity connected with the contacts of each relay, means to connect the armature of each relay with the midpoint of the winding of the other relay, one of the said connections including the armature andone, contact of a polarized sounder having its windingconnected with the armature of the other of said relays and having its other contact connected with one of the sources of potential to reverse the olarity of the current applied to the mi point of the winding of one relay when spacing signals are being sent simultaneously from both ends.

2. In a telegraph signaling system, the combination with two line circuits of two polar relays, each individual to a line circuit, one terminal of each winding being connected with its "line circuit and the other with anartificial line, sources of-potential of opposite polarity connected with the marking and spacing contacts of each of said relays, means to connect the midpoint of the winding of one relay with thearmature of the other relay, means to connect the midpoint of the winding of the said other relay with the armatufe of the said first mentioned relay, the said latter connecting means including the armature and one contact of a polarized switching means, the

winding of which is connected with the armature of the said other relay.

*3. In a telegraph signaling system, the combination with two line circuits of a repeater comprising two polar relays and polarized switching means, one winding of each of said relays being connected with one of said line circuits and the other winding of each relay with an artificial line, the

midpoint of the windings of one relay being connected with the armature of the second relay, and the midpoint of the windings of the said second relay being connected with the armature of polarized switching means having one of its contacts connected with the armature of said first mentioned relay and its second contact connected with the marking battery of said first mentioned relay, said switching means being located in a leak circuit between the armature of said second relay and ground and controlled by said second relay whereby the polarity of the current applied at the midpoint of the windings of said second relay may be reversed when both line circuits are transmitting spacing signals.

4. In a telegraph signaling system, the combination of two repeaters, each comprising two polarized relays having the armature of each relay of a repeater con nected with the windings of the other relay of said repeater, a line connecting the said repeaters, a loop circuit connected with each repeater, and means associated with each repeater to maintain the armature of one of the relays of a repeater upon its spacing contact regardless of the change of position of. the armature of the other relay whenever spacing signals are simultaneously transmitted from the-stations of both loop circuits. 7 i

5. In aftelegraph repeater, the combination of two polar relays, each having a pluralit y of primary and secondary windings, the junction point of the primary windings of one relay being connected with the armature of said second relay, and the junction point of the primary windings of said second relay being connected with the armature of a polarized sounder, one of the contacts of which is connected with the armature of said first mentioned relay, and the other contact directly connected with the marking battery of said first mentioned relay, the said sounder being controlled by the vibrating circuit of said second relay. In testimony whereof, we have signed our names to this specification this 12th day of March, 1920.

JOHN M. FELL. RALPH E. PIERCE. 

